This invention relates to systems, methods and computer programs that can be used to pace and monitor the heart. More specifically, the products and processes can be used to resynchronize several areas of the heart and assess a physiological condition, such as heart failure.
A pacemaker is a medical device that regulates the beating of the heart by delivering electrical signals to one or more sites in the heart to stimulate contractions of the heart muscle. Many modern pacemakers are also capable of sensing electrical activity in the heart and are designed to stimulate the heart when no electrical activity is sensed within a certain time period. Conventional pacemakers include single chamber pacemakers and dual chamber pacemakers. Single chamber pacemakers use one lead to sense and stimulate or “pace” the right atrium or right ventricle, while dual chamber pacemakers use two leads to sense and pace both the right atrium and right ventricle. Other pacemakers include biventricular pacemakers. Biventricular pacemakers have three leads: a first lead to pace and sense the right atrium and second and third leads to pace both the right and left ventricles, respectively. Some pacemakers have four leads: first and second leads to pace and sense the left and right atriums and third and fourth leads to pace both the right and left ventricles, respectively.
According to current statistics, 1.5 million patients have been diagnosed with congestive heart failure. This disease is associated with significant morbidity and mortality. Implanted devices, including bi-ventricular pacemakers that pace both the right and left ventricles, have gained rapid acceptance as the therapeutic standard of care for preventing heart failure. Between 25 and 30% of the newly diagnosed congestive heart failure cases each year qualify for bi-ventricular pacing. This represents 75,000 patients annually. Unfortunately, of the patients who receive bi-ventricular pacing treatment, only about 60% of those patients respond. The success of ventricular resynchronization therapy relies heavily upon proper left ventricle (LV) lead placement. A large portion (about 30-40%) of the patients who are implanted receive no benefit from the device, because current methods of electrode placement require insertion through the coronary sinus, which may or may not be close to the myocardium of the left ventricle. In addition, of the patients who agree to implant, about 8% cannot receive the device because of anatomic vessel variations in the coronary sinus which do not allow placement of the leads in the vessel at all. Significant studies are underway to determine the exact location where bi-ventricular pacing leads should be placed on the heart in order to correct the 30-40% failure rate. However, since the leads of current devices are placed through the coronary sinus, a patient's anatomy may prevent optimal placement with the current system in the majority of patients.